You need to remember something about extended warranties. You buy them thinking you need it, they sell them hoping you won't.
More people will buy them and never use it then those that do. If it were the other way around, they would not offer them.
Personally, I do not buy them. The amount of money I would invest in a warranty is not worth it to me. I would feel traped into not making my vehicle mine. Bigger tires can cause the dealer to say the problem is caused by the tires and not the fault of the vehicle. Same with exhaust systems, intakes, suspension systems, etc.
Then again, I know how to fix most anything if it does fail. The cost of most repairs is cheap. The biggies would be a tranny and engine, but I am not worried about that. I can rebuild engines and a have friends that can rebuild trannies. If anything else, I should be able to do it on my own too.
In the end it is a crap shoot. Like my uncle says, no matter what dealer you go to, no matter the brand they sell, they have a repair shop that is staffed by people and they are always busy.
Only you know what works best for you. I would hate to have an extended warranty and have the dealer blame bad ball joints being caused by my tires or lift. I can change both ball joints myself in a few hours for less then $75.00. The $2,000.00 I would have spent on the extended warranty would have been wasted.
That is just me though.
Tom